1. Field of the Invention
The present invention relates to a converter employing soft start and protection functions. In particular, the present invention relates to a switch controller for controlling a switching operation of a converter employing a soft-start and protection functions, a switch control method, a converter using the same, and a driving method thereof.
2. Description of the Related Art
In general, a converter includes a protection circuit to protect the converter from various irregular conditions. The irregular conditions may include an overload that is generated when a load connected to an output terminal increases, an output short, an output over/under voltage, and an output diode short. In the case of an overload, a drain current flowing through a switch for controlling the converter's operation increases above its normal range and reaches a threshold value. One of the conventional methods protects the converter by terminating the switching operation when the drain current reaches a threshold value in the case of an overload or an output short. The converter may be shut down for a transition period in which the load returns to a regular value. The converter may also shut down during a startup operation. This can cause a premature shutdown, when the converter is stopped before it starts its normal operation.
Typical converters have a minimum turn-on time because of an internal delay time and a leading edge blanking (LEB) time. Conventional converters do not control the drain current during the minimum turn-on time. When the converter's output terminal becomes shorted, excessive drain current flows through the switch during the minimum turn-on time, possibly damaging the switch.
The above information disclosed in this Background section is only for the enhancement of understanding and therefore it may contain information that is not prior art that is already known in this country to a person of ordinary skill in the art.